The following apparatus provides a variety of means for determining the amount of feed in an animal feeder:
In Skalka, U.S. Pat. No. 3,279,078 a fill gauge has a pivoted indicator connected to a tension member disposed downward along the corrugated side of a feed bin. when the bin is filled the tension member is forced into the corrugations the full height of the bin which pivots the indicator to the full position. As feed is removed the tension member is forced into fewer corrugations which causes the indicator to pivot correspondingly toward the empty indication.
In Skalka, U.S. Pat. No. 3,443,437 a visual indication of the amount of grain within a bin consists of a plurality of pivotally supported paddle members spaced at various elevations within the pin which are pivoted in response to the grain level. The height of the pivoted members indicating the presence of grain indicates the height of the grain.
In Pollock, U.S. Pat. No. 5,425,329 fill indicator apparatus for a feed bin uses two visual indicators. The first visual indicator is an external flag which is mechanically connected to the feed level and moved linearly along the side of the bin in response to the feed withdrawal. A second and separate visual indicator uses a second external flag which responds to an increasing level of feed as the bin is being filled to prevent the bin from being overfilled.
All of these devices require a mechanical connection to at least one part located within the feeder proper. This results in the possibility of binding or other forces from the feed disposed against the part causing an inaccurate reading. It would be desirable to be able to indicate the amount of feed remaining in a feeder without the necessity of placing any parts within the feeder subject to forces which may cause inaccuracies in the read-out or jamming of the part resulting in total reading failure.